zmisc (version 0.2.3)

zample: Sample from a vector in a safe way

Description

The zample() function duplicates the functionality of sample(), with the exception that it does not attempt the (sometimes dangerous) user-friendliness of switching the interpretation of the first element to a number if the length of the vector is 1. zample() always treats its first argument as a vector containing elements that should be sampled, so your code won't break in unexpected ways when the input vector happens to be of length 1.

Usage

zample(x, size = length(x), replace = FALSE, prob = NULL)

Value

The resulting sample

Arguments

x

The vector to sample from

size

The number of elements to sample from x (defaults to length(x))

replace

Should elements be replaced after sampling (defaults to false)

prob

A vector of probability weights (defaults to equal probabilities)

Details

If what you really want is to sample from an interval between 1 and n, you can use sample(n) or sample.int(n) (but make sure to only pass vectors of length one to those functions).

Examples

# For vectors of length 2 or more, zample() and sample() are identical
set.seed(42); zample(7:11)
set.seed(42); sample(7:11)

# For vectors of length 1, zample() will still sample from the vector,
# whereas sample() will "magically" switch to interpreting the input
# as a number n, and sampling from the vector 1:n.
set.seed(42); zample(7)
set.seed(42); sample(7)

# The other arguments work in the same way as for sample()
set.seed(42); zample(7:11, size=13, replace=TRUE, prob=(5:1)^3)
set.seed(42); sample(7:11, size=13, replace=TRUE, prob=(5:1)^3)

# Of course, sampling more than the available elements without
# setting replace=TRUE will result in an error
set.seed(42); tryCatch(zample(7, size=2), error=wrap_error)